1. Field of the Invention
The present invention relates to an improved electric switch and to an improved device containing the improved switch. More specifically, the present invention constitutes an improvement of the invention claimed in commonly-assigned U.S. patent application, Ser. No. 972,650, filed Dec. 21, 1978 in the name of Otto Meister.
The '650 application relates to a circuit-protection device which includes a first current path having a high continuous current-rating. A pair of normally electrically interconnected contacts are included in the first path. The contacts are relatively movable apart along a fixed line of direction. When the contacts move apart, the electrical interconnection therebetween is broken to open the first path. When the contacts are electrically interconnected, at least one of them defines an enclosed chamber. An ignitable device, such as a power cartridge, is included in the chamber for pressurizing it upon ignition thereof to rapidly drive the contacts apart. A second current path is in electrical shunt with the contacts. The second path physically surrounds, and has a lower continuous current-carrying rating than, the first path. Preferably, the second path includes a fusible element which may be either current limiting or non-current limiting. The first path normally shunts away from the fusible element the majority of the current through the device. When the contacts move apart, current is commutated to the fuse for interruption thereof. Preferably, the power cartridge is ignited to move the contacts apart in response to the occurrence of a fault current or other over-current in a circuit in which the device is connected. As more fully explained in the '650 application, in this way current-limiting fuses which may have high fault current interrupting ratings but low continuous current-carrying ratings may be used to protect circuits having high continuous currents, because the first path, including the contacts, normally carries the majority of the current in the circuit.